A turbofan fan case includes a containment structure designed to contain a blade released from the fan. Various designs exist, including designs employing composites, which can include a containment fabric layer, such as Kevlar®. The containment fabric is typically wrapped in multiple layers around a relatively thin, often penetrable outer wall of the fan case, positioned between the blades and the fabric layer. Thus, a released blade will penetrate the support case and strike the fabric. The fabric deflects radially, capturing and containing the released blade but largely remains intact. To avoid other fan blades from contacting the deforming case, the tip clearance between fan and case must be carefully selected. Tip clearance is, however, closely related to fan performance, and hence room for design improvement exists.